Effects of MgO on dielectric properties and electrical conductivity of ternary zinc magnesium phosphate glasses

Abstract

a b s t r a c tGlasses with composition ðZnOÞ 30 ðMgOÞ x ðP 2 O 5 Þ 70Àx (x = 5, 8, 13, 18 and 20 mol%) have been successfully prepared by the melt-quenching technique. The dielectric permittivity (e 0 ) and loss factor (e 00 ) were measured in the frequency range of 0.01 Hz to 1 MHz and in the temperature range of 303 to 573 K. From the results, there is evidence of dipolar relaxation occurring between 10 3 -10 6 Hz, while at low frequencies, the spectrum is dominated by dc conduction which was manifested by the 1=x slope of the loss factor plot. The value of the relaxing frequency (x p ) plotted against 1=T shows a single relaxation mechanism with an activation energy of 0.45 eV. The average value of the activation energy for dc conduction was much higher (1.25 eV) suggesting its diffusion movement had encountered more difficult steps than the small displacement changing dipoles. With increasing MgO concentration, the dielectric permittivity (e 0 ), dc conductivity (r dc ) and dielectric strength (De) decrease and these were attributed to some of the magnesium ions participated in the glass-forming positions as well as modifiers. At lower temperatures, the complex permittivity plots present a skewed arc with center point lying below the real axis which is a non-Debye characteristic. The empirical data were sufficiently fitted by using the Harviliak-Negami equation. The temperature dependent of the parameter a is discussed.

Anomalous dielectric constant and AC conductivity in mixed transition-metal-ion <I>x</I>Fe<SUB>2</SUB>O<SUB>3</SUB>–(20 – <I>x</I>)MnO<SUB>2</SUB>–80TeO<SUB>2</SUB> glass system

“…51 The large loss at very low frequencies (Fig. 6) was caused by DC conduction losses, which was in agreement with the previous study of Khor et al 52 The increase in energy loss with increasing temperature can be attributed to relaxation and conduction losses, which increased more rapidly with temperature. At temperature ≤343 K, such conduction losses were less related to ion migration losses and became increasingly important at higher temperatures and low frequencies.…”

Structure and electrical properties of ZnO doped barium-metaphosphate glasses

“…The E a2 value for 20 mol % ZnO content is found to be the lowest. Khor et al, [30], reported that Zn(II) cation is able to occupy network-forming sites as well as interstitial positions in glasses in this region. Although the values of E a1 vary dramatically, there is certainly an increasing trend as the concentration of ZnO increases.…”

Effect of CaO/SiO2 molar ratio on the electrical and physical properties of basaltic glass materials

“…Magnesium phosphate glasses [16] were studied to check the influence of the electrical properties of ternary zinc on magnesium oxide. The increase of magnesium oxide (MgO) concentration, leads to the participation of Mg 2+ or Ca 2+ ions in the interior structure of the glass.…”

“…This is due to the thermally-activated migration of free ions in the main glass structure. If the thermal energy is improved in the glass samples, then many charge carriers can overcome easily the attraction and diffuse long distances in the sample [16].…”